Project Summary/Abstract Non-alcoholic steatohepatitis (NASH) and resultant liver fibrosis is a major health problem in the United States and the rest of the world. Currently, there are no FDA-approved medical therapies for NASH mediated liver fibrosis, and so effective antifibrotic drugs that reverse the disease are urgently needed. Compelling evidence suggests that galectin-3 (Gal3), a beta-galactoside-binding lectin, contributes to fibrogenesis in various organs including liver as inhibition of Gal3 with carbohydrate ligands or knock down of Gal3 attenuated fibrosis. Overall, results suggest that specific inhibition of Gal3 may represent a promising therapeutic strategy against tissue fibrosis. In Galectin Therapeutics? recent phase IIb clinical trial on NASH fibrosis and cirrhosis patients, GR-MD-02 (a known Gal3 antagonist derived from modified citrus pectin, MCP) failed to achieve statistically significant data in reducing hepatic venous pressure gradient (HVPG) (primary endpoint) when the total group of patients was considered (https://seekingalpha.com/article/4140884-galectin-therapeutics-lackluster-trial- results-bad-credit-line-somehow-jump-stock-300-percent). However, a statistically significant result of GR-MD- 02 was observed only in the subgroup of NASH cirrhosis patients without esophageal varices. The failure of GR-MD-02 to treat NASH fibrosis could be attributed to its non-specificity and low affinity (10 M) to Gal3. But, Gal3?s natural affinity to its intrinsic carbohydrate ligands is in the nano molar range. The trial result also suggests that high affinity drug that can specifically target Gal3 in NASH fibrosis patients is yet to be discovered. Our scientific premise is that we have developed a very potent Gal3 antagonist, named TFD100, from a natural dietary source [PNAS, PMID: 23479624]. TFD100 binds specifically (on-target) to Gal3 with picomolar affinity ? the affinity is so high (10-100-fold more) to outcompete Gal3?s natural affinity to its intrinsic ligands. In our preliminary studies, TFD100 reduces Gal3 mediated pro-inflammatory factors and shows beneficial effect over MCP. Our research team has extensive expertise in two relevant mouse models of human Nonalcoholic steatohepatitis (NASH) and liver fibrosis: 1) High fat diet (HFD) model in C57BL/6 mice (Streptozotocin injury followed by insult with HFD) and 2) Carbon tetrachloride (CCl4) model in C57BL/6 mice. We have shown that galectin-3 expression is ~11-fold higher (p<0.001) in liver of the former mouse model at the onset of fibrosis. Based on the compelling preliminary data we hypothesize that the specific inhibition of Gal3 with TFD100 will suppress NASH mediated liver fibrosis by impeding pro-fibrotic factors. To test this hypothesis, we will first determine TFD100?s maximum tolerated dose (MTD) in C57BL/6 mice. We will then in vivo determine TFD100?s ability to treat NASH mediated liver fibrosis in our two mouse models. After drug treatment, liver tissue will be examined for histopathology evaluation, including deposition of collagen (primary endpoint), hepatocellular fat accumulation, hepatocyte ballooning, intra-portal and intra-lobular inflammatory infiltrate. We will also determine changes in pro-fibrotic factors and cell fate after TFD100 administration in vivo. Particularly, we will measure the levels of cytokines and other genes such as TGFb, ILs, collagens, Gal3, and extracellular matrix proteins. We will determine differential expression of liver markers and pro- inflammatory/fibrotic immune cell frequencies. This study, for the first time, will explore the therapeutic utility of a very potent natural carbohydrate compound that outcompetes Gal3?s natural affinity to treat NASH mediated fibrosis.